Forming method and apparatus



April 1, 1969 J. A. SCALETTA ET AL 3,435,653

FORMING METHOD AND APPARATUS Filed Jan. 21, 1966 Sheet I of 2.-

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JOSEPH A. SCALETTA ROLAND E. MILLER JOHN VALEK BY tfidmm Zum aa, ang-ATTORNEYS FORMING METHOD AND APPARATUS qa H$ JOSEPH A, emLcr'rA ROLANDMILLER JOHN VALEK BY 6m I ATTORNEYS United States Patent 3,435,653FORMING METHOD AND APPARATUS Joseph A. Scaletta, Chicago, Roland E.Miller, Orangeville, and John Valek, Cicero, Ill., assignors to NationalDairy Products Corporation, Chicago, Ill., a corporation of DelawareFiled Jan. 21, 1966, Ser. No. 522,284 Int. Cl. B21d 11/04 US. Cl. 72-3369 Claims ABSTRACT OF THE DISCLOSURE In a method and apparatus forforming drawn containers from a metallic blank, the edge portion of theblank is clamped between a pair of opposed clamping members during thedrawing operation, with the magnitude of the clamping force beinglimited to a predetermined maximum which will permit a gradual but notcomplete withdrawal of the blank from between the clamping members. Allof the clamping force is relieved so as to release the edge portion ofthe blank before the stress in the edge portion is suflicient tofracture the blank and before any portion of the edge portion has becomefully withdrawn from between the clamping members.

This invention relates generally to a forming method and apparatus, andmore particularly it relates to a method and app-artus for drawingcontainers having a formed rim in a single stroke of the formingapparatus.

In recent years it has been increasingly desirable to form containersfrom lightweight thin metal stock, such as aluminum and aluminum alloystock, reduced tin plate, double drawn steel and other lightweightmaterials by a drawing operation. Such containers are lightweight,easily handled, have good strength as compared to paper containers, andpresent attractive consumer packages. The container is preferablyconstructed with a formed rim which may take the shape of a curled orrolled bead or a generally flat flange. A particularly desirablecontainer is one having a curled rim thereon for appearance and also forsealing of the lid onto the container. However, it has not beenconvenient to draw lightweight containers having a formed rim in asingle stroke of the forming apparatus. It has been particularlydifficult to draw such containers having a large depth as compared tothe diameter, generally referred to as deep drawn containers.

Heretofore, it has been difiicult to form deep drawn containers having acurled rim from lightweight stock, for example, aluminum. Aluminum has alow tensile strength and the edges of the aluminum blank tear and formslivers of material during the drawing operation, leaving an uneven andunsightly rim on the container and causing the interior of the die tobecome obstructed by the slivers of aluminum torn from the blanks. Thisproblem has been partially overcome in the post by forming deep drawnlightweight aluminum containers having a relatively wide flange in adrawing operation, removing the excess flange by trimming in anotheroperation, and thereafter rolling or crimping the flange into a curledrim in a separate operation. Deep drawn containers having a curled rimformed in this manner are time consuming to produce, require a number ofdies, and the plural drawing operations result in the formation of roughspots and uneveness in the sidewall of the container, and it would beadvantageous to provide a method and apparatus for forming a deep drawncontainer having a curled rim from lightweight aluminum or aluminumalloy stock material in a single drawing operation.

Patented Apr. 1, 1969 It is the principal object of the presentinvention to provide a method and apparatus for forming drawncontainers. A further object is to provide a method and apparatus forforming deep drawn containers having a curled rim thereon in a singledrawing operation. An additional object is to provide an improvedclamping mechanism which provides improved control over the containerdrawing operation, and eliminates tearing of the stock and the formationof slivers during the drawing operation.

'Fhese and other objects of the invention may be readily understood fromthe following detailed description and from the drawings of which:

FIGURE 1 is a partial schematic view of a form- 7 ing press and itsassociated hydraulic actuating system, portions of the forming pressbeing illustrated in vertical cross-section;

FIGURE 2 is a graph showing the hydraulic pressure on the draw ring of aforming press as a function of the rotation of the press crankshaft;

FIGURE 3 is a partial cross-sectional rview of the forming press ofFIGURE 1, the press being shown in the position where the blank has beencut from the stock material;

FIGURE 4 is similar to FIGURE 3 and shows the press in a partiallyclosed position;

FIGURE 5 is similar to FIGURES 3 and 4 and shows the press in a fullyclosed position; and

FIGURE 6 is similar to FIGURE 5 and shows the press after formation of acurled rim on the container.

Very generally, the present invention is directed to a method andapparatus for forming drawn containers having a formed rim in a singlestroke of a forming press without attendant problems of slivering andtearing of the edges of the stock material during the forming operation.More specifically, the present invention is directed to a forming presswhich includes means for forming a blank of stock mateiral to be drawn,means for clamping the edges of the blank during the drawing operation,means for controlling the clamping pressure on the edges of the blank,and means to release the clamping pressure at a particular point duringthe drawing operation, and to a method of forming deep drawn containersutilizing such a forming press. The invention also contemplates ahydraulic actuated clamping mechanism for clamping and releasing theedges of the blank during the drawing operation.

It has been found that in accordance with the present invention it ispossible to provide a deep drawn container of suitable lightweight stocksuch as aluminum or aluminum alloy stock in a single drawing operationwithout slivering of the stock material. The method and apparatus of theinvention are particularly useful in forming a deep drawn containinghaving a curled rim thereon, such as is desired where the container isto be sealed with a cover. Of course, the invention is also useful indrawing shallow containers.

Referring now to FIGURE 1 there is shown a partial schematic elevationalcross-sectional view of a die set 11 of a forming press for forming deepdrawn cylindrical containers, and a hydraulic actuating mechanism 12 forcontrolling the clamping pressure on the edges of the blank during thedrawing operation. It is understood that the parts of the forming pressnot illustrated, such as the ram, crankshaft, and auxiliary supportmembers, may be of any desired configuration, and do not form a portionof the present invention.

The press die set 11 includes an upper punch holder 13 and a lower dieholder 15. An annular blanking punch 17 is carried by the punch holder,and a cylindrical forming punch 19 is slideably carried within theannular blanking punch 17. One or more hydraulic cylinders 21 having aliner 23 are provided in the punch holder 13. A piston 25 is disposedwithin the cylinder 21, the piston having a shaft 27 extending from. thecylinder 21 and abutting the upper surface of the forming punch 19 forcontrolling the movement of the forming punch 19 relative to theblanking punch 17 as explained hereinafter. The hydraulic cylinders 21is connected to a source of fluid pressure which may be a sump 55 andpressure booster 57 of the hydraulic actuating system 12, or may be aseparate hydraulic system, by means of a bore 29 and conduit 30. Asolenoid or other suitably operated valve 32 is provided in the conduit30 for controlling the pressure in the conduit 30. A stripper plate 31,which may be spring mounted, surrounds the blanking punch and acts tofree the stock from the punch 17 at the end of each stroke of the press.

The die holder 15 supports a backing plate 33 upon which is supported anannular yoke 35. An annular draw ring 37 is concentrically mountedwithin the cavity in the yoke 35 and is adapted for sliding movementrelative to the yoke. An annular groove 38 is provided in the draw ring37 for forming a curled rim on the container as described hereinafter. Acylindrical forming die 39 is mounted on the backing plate 33 centrallyof the annular draw ring 37 in a mating position with the forming punch19 carried by the punch holder 13. The draw ring 37 and the blankingpunch 17 cooperate in a manner as hereinafter described to form agripping means for aligning and gripping the edge of the blank duringthe drawing operation.

One or more hydraulic cylinders 41 are provided in the die holder 15beneath the draw ring 37 and each is provided with a cylindrical liner43. A piston 45 is mounted for reciprocating movement within each of thehydraulic cylinders 41, and a shaft 47 is connected to the upper endthereof extending through the backing plate 33. The upper end of theshaft 47 abuts the lower surface of the draw ring 37 and the shaft is ofa length so that when the piston 45 is in its uppermost position, asshown in FIGURE 1, the upper surface of the draw ring 37 is even withthe upper surface of the yoke 35.

A bore 49 is provided in the die holder 15 in fluid communication withthe hydraulic cylinders 41, the bore being connected in fluidcommunication to a conduit 51 of the hydraulic actuating system 12. Thehydraulic actuating system 12 includes a sump or reservoir 55 forhydraulic fluid connected to the bore '49 by means of the conduit 51. Apressure booster 57 is positioned in the conduit 51 between the sump 55and the bore 49. The pressure booster 57 may be connected to a suitablesource of air under pressure, not shown, and operates to insure that thehydraulic system 12 and the cylinders 41 are constantly filled withhydraulic fluid. The pressure booster 57 may be controlled by means of asuitable switch 59, which in the embodiment of the invention illustratedin FIGURE 1 is actuated by a cam 61 in response to the stroke of thepress as described hereinafter.

A check valve 63 is positioned in the conduit 51 between the booster 57and the cylinders 41 to prevent backflow of hydraulic fluid from thecylinders into the booster during the drawing operation. A pressurerelief valve 65 is connected in fluid communication with the conduit 51between the check valve 63 and the cylinders 41. The pressure reliefvalve 65 is normally closed and is set to open and relieve the pressurein the cylinders 41 and conduit 51 at a fixed pressure determined by theoperating conditions of the press, and it is desirable that the pressureat which the pressure relief valve 65 opens be adjustable for differentforming operations and for different materials. As shown in FIGURE 1,the pressure relief valve is connected by a conduit 67 to the sump 55 sothat the hydraulic fluid exhausted from the cylinders 41 is returned tothe sump 55.

Means are also provided in the hydraulic actuating system to rapidlyrelieve the pressure in the cylinder 41, and to consequently relieve thegripping pressure between the blanking punch 17 and the draw ring 37during a particular portion of the drawing operation. As shown in FIGURE1, such means includes a dump valve 69 positioned in a conduit 71connected to the conduit 51. The dump valve is utilized to rapidlyrelieve or exhaust substantially all of the pressure within thehydraulic cylinders during a particular portion of the forming operationas described hereinafter. Preferably, the hydraulic fluid exhausted fromthe cylinders 41 by the dump valve 69 is returned to the sump 55 by theconduit 71. The dump valve 69 is preferably a fast acting valve, such asa solenoid valve, and may be controlled by a switch 73 responsive to thestroke of the press. The switch 73 may be actuated by a suitable cam 75which is carried by a crank shaft on the press. The cam 75 is adjustedto actuate the switch during a desired portion of the stroke of thepress, thereby instantly relieving the pressure within the hydrauliccylinders 41 and the gripping pressure between the blanking punch 17 andthe draw ring 37.

In accordance with the present invention, the dump valve 69 is openedfor only a short period of time during each stroke of the press and thecam 75 is contoured accordingly.

The operation of the forming press and the hydraulic actuating system 53may be readily understood by reference to FIGURES 1 through 6.

The operation of the press is explained in connection with the formationof a deep drawn container having a curled rim from 0.009 gauge aluminumstock. The container is 1.37 inches deep and has an outside diameter of4.066 inches and an inside diameter of 3.878 inches. The container isdrawn from a circular blank having a diameter of 6.188 inches, and thecurled rim formed on the finished container has a diameter of 0.09 inch.FIG- URE 1 shows the position of the press at the beginning of a strokeor cycle of the press at the point where the punch holder 13 and dieholder 15 are separated and a sheet of stock material 77 from which thecontainer is to be formed is fed therebetween.

FIGURE 2 is a graph of the pressure in the hydraulic cylinders 41 versusthe degrees of rotation of the press crankshaft, in the manufacture ofthe described container. At the beginning of the stroke of the press,the position of FIGURE 1, the crankshaft is at zero degrees rotation.

FIGURES 3 to 6 are partial sectional elevational yiews, similar toFIGURE 1, of the forming press, and illustrate the movement of the pressduring one stroke thereof for forming the described deep drawn containerhaving a curled rim.

At the beginning of the stroke of the press (FIGURE 1) the punch holder13 and the die holder 15 are separated and the stock material is fedtherebetween by the press feed mechanism. The press crankshaft thencommences rotation, causing the punch holder 13 and the die holder 15 tomove toward each other to begin the drawmg operation. For purposes ofillustration, FIGURES 3 to 6 show the die holder as being stationary andthe punch holder as reciprocating down and up during each stroke of thepress. At the beginning of the stroke of the press, the draw ring 37 isin its uppermost position, FIGURE 1, and the hydraulic cylinders 41 arefilled with hydraulic fluid due to the action of the booster 57 duringthe previous stroke of the press. The pressure in the cylinders 41 isrelatively low, about 50 p.s.i.g. as seen in FIGURE 2. The pressurerelief valve 65, which may be set to open at a pressure of about 1200p.s.i.g., is closed and the cam actuated dump valve 69 is also closed.The check valve 63 prevents back flow of hydraulic fluid from thecylinders 41 and it can be seen that a closed and filled hydraulicsystem is established which acts to retain the draw ring 37 in itsextended position.

Continued rotation of the crankshaft causes the punch holder 13 to beginits downward travel, and the blanking punch 17 engages the stockmaterial 77. As the punch holder 13 continues its downward travel, theblanking punch punches the blank 79 from the stock, the relativeposition of the components at that point bing illustrated in FIGURE 3.As seen in FIGURE 3, as the blank 79 is being punched from th stock 77by the blanking punch 17, the downward movment of the blanking punch 17causes the draw ring 37 to be slightly depressed from its fully extendedposition in which it is even with the upper surface of the forming dieand the die yoke. Since the hydraulic system 12 is full of hydraulicfluid, and since the pressure relief valve 65 and dump valve 69 areclosed and the check valve 63 prevents back flow of hydraulic fluid intothe booster, the dawnward movement of the blanking punch 17, and theconcurrent downward movement of the draw ring 37, causes the pressure inthe hydraulic cylinders 41 to begin to increase. As seen in FIGURE 2,this occurs after about 120 rotation of the press crankshaft.

The downward pressure of the blanking punch 17 and the upward pressureof the draw ring 37 on the edge portion 81 of the blank 79 heldtherebetween grips the edge 81 of the blank 79 securely during thedrawing operation. As the press crankshaft continues to rotate, thepunch holder 13, blanking punch 17 and draw ring 37 continue to traveldownwardly against the hydraulic pressure in the cylinders 41. As seenin FIGURE 2, the pressure in the cylinders 41 rises sharply, thusincreasing the gripping pressure on the edge 81 of the blank 79, and theblank 79 begins to be stretched and formed over the forming die 39(FIGURE 4). The increase in the pressure in the hydraulic cylinders 41causes a concurrent increase in the gripping pressure applied to theedge 81 of the blank 79. An increasing gripping pressure is desired asthe drawing operation continues due to increased tensile forces exertedduring drawing and stretching of the blank into the desired shape. Thedesired gripping pressure may be adjusted for a particular drawingoperation by proper selection of the size of the pistons 45 and thepressure established in the cylinders 41 at the beginning of the drawingoperation.

In order to provide a deep drawn container in a single stroke of theforming press, the gripping pressure applied to the edge 81 of the blank79 by the blanking punch 17 and the draw ring 37 is selected so that asthe drawing operation proceeds the tensile forces applied to the edge 81of the blank 79 by the stretching of the blank during the drawing aresuflicient to cause the edge 81 to be slowly pulled from between theblanking punch 17 and the draw ring 37. As seen in FIGURE 4, the edge 81of the blank 79 has partially withdrawn from between the blanking punch17 and the draw ring 37.

As the punch holder 13, blanking punch 17 and draw ring 37 continuetheir downward movement, the drawing operation proceeds and the pressurein the hydraulic cylinders 41 continues to build up until thepreselected maximum pressure is reached, at which time the pressurerelief valve 65 opens and the hydraulic fluid is exhausted to the sump55. As seen in FIGURE 2, if the pressure relief valve is set to open ata pressure of about 1200 p.s.i.g., the maximum pressure established inthe cylinders 41 is 1200 p.s.i.g. At a pressure of 1200 p.s.i.g. thetensile forces created in the blank during the forming operationcontinue to withdraw the edge 81 of the blank from between the blankingpunch 17 and the draw ring 37 As the punch holder 13 continues itsdownward travel, the forming punch 19 engages the blank and thecontainer is shaped between the forming punch 19 and the forming die 39.At the same time the annular edge 81 of the blank 79 continues to befurther withdrawn from between the blanking punch 17 and the draw ring37.

In accordance with the present invention, and in order to provide a deepdrawn container in a single stroke drawing operation without sliveringor tearing of the blank,

the gripping pressure applied to the edge 81 of the blank 79 is releasedjust prior to the time at which the edge of the blank would be pulledfrom between the gripping means by the tensile forces created in theblank during the drawing operation. In the manufacture of the describedcontainer, the gripping pressure is released by actuation of the dumpvalve 69 at the point when about to it, of an inch of the edge 81 of theblank 79 is held between the draw ring 37 and the blanking punch 17. Thedump valve 69 is actuated by the cam 75 which is carried by the presscrankshaft to rapidly relieve the pressure within the hydrauliccylinders 41 which releases the edge 81 of the blank 79 from between theblanki g punch 17 and the draw ring 37. This release of the pressurewithin the cylinder is timed so as to coincide with the bottoming ormating of the forming punch 19 and the forming die 39.

The actuation of the dump valve 69 is carried out at a point betweenabout and of rotation of the cam 75, as shown in FIGURE 2. Between theportion of the stroke of the press wherein the crankshaft rotates fromabout 161 to about 178, there is substantially no pressure within thehydraulic cylinders 41 except for a static pressure of 40 to 50p.s.i.g., and the blanking punch 17 and the draw ring 37 bottom out asshown in FIGURE 5. During the last portion of the downward travel of thepunch holder, and after being released from the gripping means, the edge81 of the blank 79 is wiped between the side of the forming die 39andthe side of the blanking punch 17 to form a straight annular rim(FIGURE 5 When the press crankshaft has rotated to about 178, the cam 75opens the switch 73 and the dump valve 69 is closed. At about the sametime the cam 61, which may also be carried by the press crankshaft,actuates the air booster 57 to force hydraulic fluid through the checkvalve 63 and the conduits 30 and 51 into the hydraulic cylinders 21 and41. The pressure within the hydraulic cylinders 41 is increased rapidlyand causes the draw ring 37 and blanking punch 17 to move upwardly.During the initial upward travel of the draw ring 37, the annular rim ofthe container is engaged by the groove 38 in the draw ring 37 and isformed into a curl, as shown in FIGURE 6. At the same time, thehydraulic fluid under pressure introduced into the cylinders 21 causesthe forming punch 19 to remain in engagement with the forming die 39 inorder to hold the container stationary during formation of the curledrim. The relative movement of the blanking punch 17, draw ring 37, andforming punch 39 during formation of the curled rim can be seen fromFIGURES 5 and 6.

After the curl has been formed on the annular rim, the punch holder 13and the die holder 15 separate and the container is ejected by means ofa knockout pin 83. During this time, the pressure in the hydrauliccylinders 41 causes the draw ring 37 to move upwardly until it returnsto the position of FIGURE 1. The valve 32 is also opened to relieve thepressure in the cylinders 21.

Although the invention has been described and is illustrated asincluding a separate dump valve and a separate pressure relief valve, itis contemplated that both functions might be performed by a single valveif desired. Such a valve should include a pressure relief mechanism forrelieving the pressure within the hydraulic cylinders when the pressureexceeds the desired amount, and also includes a solenoid or other meansof actuation for overriding the pressure relief and dumping thehydraulic fluid from the hydraulic cylinders to relieve the grippingpressure during that portion of the stroke of the press where it isdesired to release the edge of the blank from between the blanking punchand the draw ring.

It is also contemplated to utilize a solenoid operated dump valve 69, asillustrated in FIGURE 1, and to also include an overriding mechanism inthe pressure responsive valve 65 so that both the dump valve and thepressure responsive valve may be utilized to rapidly relieve thepressure from the hydraulic cylinders at the point that it is desired torelease the edge of the blank from between the blanking punch and thedraw ring. It has been found to be particularly desirable to relieve thepressure within the hydraulic cylinders as rapidly as possible and ithas been found that the use of two lines and two valves to dump thefluid pressure has provided generally better results than a single line,particularly where the fluid lines and the valves have a small capacity.

It is also contemplated to utilize a heat exchanger in one or more ofthe lines of the hydraulic actuating system in order to maintain thehydraulic fluid at a constant temperature and to avoid expansion andcontraction.

Although various features of the present invention have been disclosedin particularity in order to describe the invention, various alternativeembodiments within the skill of the art are contemplated.

Various of the features of the invention are set forth in the followingclaims.

We claim:

1. A method for forming drawn containers, said method comprisingdisposing essentially the entire edge portion of a blank from which thecontainer is to be formed between a pair of opposed clamping members andapplying a clamping force thereto by means of said clamping members,effecting contact between the blank and a drawing die to commence adrawing operation while maintaining the clamping force on the blank,limiting the magnitude of the clamping force on the blank to apredetermined maximum so as to permit a gradual but not completewithdrawal of the blank from between the clamping members as the drawingoperation progresses, relieving essentially all of the clamping force soas to release the edge portion of the blank before the stress in theedge portion of the blank is sufficient to fracture the blank in suchedge portion and before any portion of said edge portion has becomefully withdrawn from between the clamping members, drawing the edgeportion so released around the die, and forming the released edgeportion of the blank into a bead while maintaining the blank stationaryrelative to the drawing die.

2. A method in accordance with claim 1, wherein the blank is separatedfrom a larger piece of sheet metal after the blank has been clamped andbefore the blank has been drawn to any appreciable extent.

3. A press for forming drawn containers, said press comprising a pair ofopposed clamping members adapted to engage therebetween essentially theentire edge portion of a blank to be formed, means for applying aclamping force to said edge portion of said blank by means of saidclamping members, a drawing die, means for effecting contact between theblank and said drawing die to commence a drawing operation whilemaintaining the clamping force on the blank, means for limiting themagnitude of the clamping force on the blank to a predetermined maximumso as to permit a gradual withdrawal of the blank from between theclamping members as the drawing operation progresses, means forrelieving essentially all of the clamping force so as to release theedge portion of the blank before the stress in the edge portion of theblank is suflicient to fracture the blank in such edge portion andbefore any portion of said edge portion has become fully withdrawn frombetween the clamping members, means for drawing the edge portion soreleased around the die, and means for forming the released edge portionof the blank into a head while maintaining the blank stationary relativeto the drawing die.

4. A press in accordance with claim 3, wherein an hydraulic system isprovided for applying a clamping force to the edge portion of the blankby means of said clamping members, said hydraulic system includingpressure responsive means for limiting the magnitude of the clampingforce.

5. A press for forming drawn containers in accordance with claim 4,wherein said hydraulic system further includes a sump for hydraulicfluid, a conduit providing pressure-responsive communication between thehydraulic fluid in said sump and a blank-engaging portion of saidclamping means, a dump valve in communication with the fluid in saidconduit for rapidly relieving the fluid pressure exerted against saidblank-engaging portion of said clamping means, and means for actuatingsaid dump valve.

6. A press in accordance with claim 5, wherein means are providedresponsive to the stroke of the press to open and close said dump valveduring the forming operation, and wherein further means are provided forincreasing the fluid pressure applied to said blank-engaging portion ofsaid clamping means subsequent to the opening and closing of said dumpvalve.

7. A press in accordance with claim 6, wherein said pressure-increasingmeans is a pressure booster in said conduit, wherein means are providedresponsive to the stroke of the press for actuating said pressurebooster to rapidly increase the pressure applied to said blankengagingportion of said clamping means subsequent to the opening and closing ofsaid dump valve.

8. A press in accordance with claim 3, wherein said clamping meanscomprises a blanking punch for forming a blank from a sheet and a drawring positioned opposite said blanking punch, and wherein said draw ringis provided with a groove adapted to engage the edge of the blank andform said edge into a curled rim.

9. A press in accordance with claim 3, wherein means including ablanking punch are provided for forming the blank from a sheet, whereina forming punch is slidably carried within said blanking punch, andwherein means are provided responsive to the stroke of the press forexerting pressure against said forming punch.

References Cited UNITED STATES PATENTS 1,482,732 2/ 1924 Calleson 72-3512,192,778 3/ 1940 Stacy 72-351 3,085,530 4/1963 Williamson 72-3513,147,722 9/ 1964 Williamson 72-351 3,292,415 12/ 1966 Hoflman 72-3513,296,850 1/ 1967 Fiore 72-351 RICHARD J. HERBST, Primary Examiner.

US. Cl. X.R. 72-35 1 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,435 ,653 April 1, 19'

Joseph A. Scaletta et al.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shovm below:

Column 1 line 59, "post" should read past Column 2, line 38 "mateiral"should read material line 54, "containing" should read container Column3, line 7, "cylinders" should read cylinder Column 4, line 30, "1.37inches" should read 1.73 inches Column 5, line 5, bing should read beingline 7, "th" should read the line 15, "dawnward should read downwardSigned and sealed this 14th day of April 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, I

Commissioner of Paten Edward M. Fletcher, Jr.

Attesting Officer

